Solid-phase immunodetermination is usually carried out in one vessel so that the analyte to be determined in the sample is first allowed to react with a separating reagent bound in a solid phase, whereupon the other determination steps are carried out in the same vessel. The troublesome thing here is that you must do much dosing and removing of fluids. When there are several different determinations, a large stock of different reagents is also required.
Specification EP-A-194789 also presents a system, wherein the determination is carried out by using several vessels. The solid phase is formed by a thin strip which is moved from one vessel to another. The vessels contain the reagents needed in the determination method.